1. Technical Field
The present invention relates to a method of making N-type semiconductor layer and a method of making N-type thin film transistors with the N-type semiconductor layer.
2. Description of Related Art
A typical thin film transistor (TFT) is made of a substrate, a gate electrode, an insulation layer, a drain electrode, a source electrode, and a semiconducting layer. The thin film transistor performs a switching operation by modulating an amount of carriers accumulated in an interface between the insulation layer and the semiconductor layer from an accumulation state to a depletion state, with applied voltage to the gate electrode, to change an amount of the current passing between the drain electrode and the source electrode.
The N-type semiconductor layer is usually manufactured via doped method or depositing oxide layer at high temperature higher than 250° C. However, the method of making doped N-type semiconductor layer is complex, and the doped N-type semiconductor layer is limited in stability. Furthermore, the flexible substrate cannot sustain high temperature, and the deposition method cannot be compatible with the semiconductor process. Thus the N-type semiconductor layer is hard to form on the flexible substrate.
What is needed, therefore, is a method of making N-type semiconductor layer and a method of making N-type TFT that can overcome the above-described shortcomings.